Dynamo transformation of the collisional R–T in a weakly ionized plasma

Theoretical prediction of a new kind of normal mode behaviour of electro-mechanical nature was first time reported by Dwivedi and Das in 1992 in the context of mesospheric modeling of observed neutral induced turbulence. Local dynamo action (due to relative neutral flow) governs the basic physical principle for linear excitation of the neutral induced low frequency instability (NILF) in mesospheric plasma, which comprises of weakly ionized inhomogeneous gas confined by the external gravity and ambient magnetic field. The present contribution offers physical explanation in terms of dynamo transformation of neutral drag effect as a source to understand complete suppression of the usual collisional R-T and in turn linear driving of the NILF. It is therefore emphasized, worth calling it as the dynamo instability.     

临近空间大气环境研究现状

临近空间指高度位于(20$\sim$100)\,km之间的地球大气层.简要综述临近空间的已有了解和研究前沿,包括基本状态、主要过程与控制因子.介绍了基于已有探测资料的经验模式的建立和基于基本物理定量规律和数值模拟方法的中层大气环流和化学气候数值模拟.最后从临近空间大气环境保障应用角度提出研究的新建议.      

东经120°E中间层和低热层纬向风结构及变化特征

利用热层-电离层-中间层能量和动力学卫星（TIMED）上搭载的多普勒干涉仪（TIDI）获取的为期9年的纬向风数据,考察了东经120°E子午圈中间层和低热层（MLT）平均纬向风的典型结构和变化特征．结果表明,在热带外尤其是中高纬度地区,TIDI观测结果与当前通用的中层大气经验模式有较好的一致性．但是在热带地区,观测与模式显著不同．在TIDI测量覆盖的所有高度（80-105km）上,热带地区纬向风持续地表现为东风,形成一个以赤道为中心的东风带．为期9年的观测数据显示,该东风带的宽度平均为37．5°,平均变化幅度约为14°．     

Correction of temperature influence on the wind retrieval from a mobile Rayleigh Doppler lidar

A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km-60 km away from ground.Before the inversion of the Doppler shift due to wind,the Rayleigh response function should be calculated,which is a convolution of the laser spectrum,Rayleigh backscattering function,and the transmission function of the Fabry-Perot interferometer used as the frequency discriminator in the lidar.An analysis of the influence of the temperature on the accuracy of the Une-of-sight winds shows that real-time temperature profiles are needed because the bandwidth of the Rayleigh backscattering function is temperature-dependent.An integration method is employed in the inversion of the temperature,where the convergence of this method and the high signal-to-noise ratio below 60 km ensure the accuracy and precision of the temperature profiles inverted.Then,real-time and on-site temperature profiles are applied to correct the wind instead of using temperature profiles from a numerical prediction system or atmosphere model.The corrected wind profiles show satisfactory agreement with the wind profiles acquired from radiosondes,proving the reliability of the method.     

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根据尘埃等离子体理论,考虑到尘埃粒子的充放电过程,研究了尘埃冰晶粒子吞噬效应对极区中层电子浓度分层结构及电导率和介电常数的影响。结果表明,尘埃冰晶粒子的吞噬效应造成了极区中层80~90km高度范围内电子浓度的分层结构,并进而导致这一区域尘埃等离子体电导率、介电常数沿高度出现明显的分层,为解释和研究极区中层夏季回波现象提供参考。     

基于尘埃等离子体理论的极区中层分层结构研究

根据尘埃等离子体理论,考虑到尘埃粒子的充放电过程,研究了尘埃冰晶粒子吞噬效应对极区中层电子浓度分层结构及电导率和介电常数的影响。结果表明,尘埃冰晶粒子的吞噬效应造成了极区中层80~90km 高度范围内电子浓度的分层结构,并进而导致这一区域尘埃等离子体电导率、介电常数沿高度出现明显的分层,为解释和研究极区中层夏季回波现象提供参考。     

Catalytic effect investigation of α-Fe2O3 and α-Fe2O3-CMS nanocomposites on the thermal behavior of NC/DEGDN mixture: DSC measurements and kinetic modeling

In this work, the thermal behavior and kinetics of energetic systems containing α-Fe₂O₃ and iron oxide–carbon mesospheres (α-Fe₂O₃-CMS) with nitrocellulose (NC)/diethylene glycol dinitrate (DEGDN)-based composites have been investigated using differential scanning calorimetry DSC and four isoconversional kinetic methods, respectively. The obtained results indicate that NC/DEGDN show only one decomposition peak, corresponding to the decomposition of the nitrate esters. Furthermore, the introduction of α-Fe₂O₃ and α-Fe₂O₃-CMS have lowered the peak temperature by 3.1 °C and 4.7 °C, respectively. Besides, the activation energy of the thermal decomposition of NC/DEGDN was decreased by 11.9 kJ/mol and 27.97 kJ/mol, after the introduction of α-Fe₂O₃ NPs and α-Fe₂O₃ NPs supported on CMS. These results confirm the good catalytic effect of the added catalysts on the thermal decomposition of the NC/DEGDN mixtures. However, the best catalytic effect was provided by the α-Fe₂O₃-CMS. Furthermore, the three considered systems were found to decompose according to different integral models g(α).     

The study and applications of photochemical-dynamical gravity wave model Ⅱ-- The effects of stable gravity wave on chemical species distribution in mesosphere

A nonlinear, compressible, non-isothermal gravity wave model that involves photochemistry is used to study the effects of gravity wave on atmospheric chemical species distributions in this paper. The changes in the distributions of oxygen compound and hydrogen compound density induced by gravity wave propagation are simulated. The results indicate that when a gravity wave propagates through a mesopause region, even if it does not break, it can influence the background distributions of chemical species. The effect of gravity wave on chemical species at night is larger than in daytime.